The present invention relates to a system for automatically lowering the temperature of a room or a house during certain periods such as the nighttime hours utilizing the conventional two-conductor wiring from the furnace to the thermostat control. In this regard, it will be appreciated that in veiw of the national need to conserve energy, it is highly recommended that home temperatures be lowered every evening. As a practical matter, home owners will be less likely to effect a nightly temperature reduction if he must remember to adjust the thermostat each night and must arise to a cold house each morning and then readjust the thermostat. Consequently, the advantages of an automatic system for reducing the temperature setting of the thermostat each night and for increasing the temperature setting just prior to the usual awakening time are apparent.
It will be appreciated that if the installation of an automatic system requires the trouble and expense of replacing or supplementing the existing wiring from the thermostat to the furnace or the automatic system is costly, home owners will be discouraged rather than encouraged to save energy through the installation of an automatic temperature reduction system.
The present invention provides an automatic temperature reduction system for a room or house which is straightforward in construction so that it may be manufactured at low cost, and additionally, utilize the two existing conductors of the conventional thermostat wiring. The present invention achieves these advantageous results by providing a temperature control system utilizing a heat source which is associated with the temperature responsive element in the heated area and which is activated during the nighttime hours to make the apparent room temperature appear to be higher than the actual room temperature thereby causing the temperature responsive element to signal for a reduction in room temperature. A clock-controlled adjustable current source for the heater is located near the usual furnace control. Steering circuitry such as a first pair of diodes at the furnace control and heater current source location and a second pair of diodes at the temperature responsive element and heater location is provided for directing one-half of an alternating current waveform through the furnace control and the temperature responsive element, and the other half of the alternating current waveform through the heater current source and the heater so that the furnace temperature control can be independently controlled by the temperature responsive element and the heater can be independently controlled by the heater current source by using respective halves of the waveform for each control function.